Spring return mechanisms bias a movable member to return to a neutral position, or starting position. Power springs (or clock springs) and torsion bars are the types of springs that are used in spring return mechanisms.
Vehicle seats may include recliner mechanisms that are used to position a seat back in a selected angular orientation relative to a seat base. Recliner mechanisms generally include selectively lockable pivotable plates. Two recliner mechanisms are usually provided on the inboard and outboard sides of the vehicle seat. The two recliner mechanisms on opposite sides of the vehicle seat may be interconnected by a connecting rod that coordinates locking and unlocking of the two recliner mechanisms on opposite sides of the vehicle seat.
When a vehicle seat is repositioned to change the tilt angle of the seat back relative to the seat base, the seat occupant generally pushes back against the seat back while the recliners are unlocked. A pair of wound torsion springs or torsion bars may be provided in a vehicle seat back to bias the seat back to move in the forward vehicle direction. The wound torsion springs or torsion bars apply a force to the seat back urging the seat back to a more upright position. Wound torsion springs increase the cost of vehicle seats and require space inside the seat that increases the total space required for the seat recliner mechanism. The wound torsion springs must be assembled to the vehicle seat back and recliner hinges during the seat assembly process.
Some vehicle seats are folded in two different directions to be stored or to be moved in a tilt-and-tumble operation. It may be desirable to provide assistance with lifting a seat component in both clockwise and counter-clockwise directions but to do so with conventional power springs, two separate sets of springs are required. Power springs are usually only used in a compressive direction. Using power springs to create a biasing force by expanding the spring is not generally recommended. Using two sets of springs increases space requirements and also increases cost.
There is a need for a recliner return spring that reduces the cost of the vehicle seat, simplifies assembly and reduces the package space required for the return spring mechanism. There is also a need for a bi-directional spring that can provide a spring assist in both rotational directions while minimizing cost and space requirements.
Applicants have developed a split tube spring that addresses the above problems and others as will be understood by one of ordinary skill in the art.